Integrated circuits for use by military contractors must be tested according to procedures set forth by the Department of Defense in MIL-STD-883C, Military Standard Test Methods and Procedures for Microelectronics.
Method 1009.8 of MIL-STD-883 specifies an accelerated laboratory corrosion test simulating the effects of sea coast atmosphere on device and package elements. This test requires that side braze and ceramic dual in-line packaged parts be placed in the atmospheric salt chamber in such a way that the package lids face up at a 45.degree. angle. Pin grid arrays are to be placed in the testing chamber such that half the samples are situated with their caps or lids facing up at a 45.degree. angle and half the caps or lids are situated facing down at a 45.degree. angle. Additional test requirements specify that nothing shall touch the metalized surfaces of the packaged parts and that all surfaces must be uniformly exposed to the freely settling fog within the testing chamber.
These testing requirements create a difficult problem particularly in positioning and holding the packaged parts in the chamber for the duration of the test at the specified position and without contact to the metalized surface. Prior attempts to resolve these problems and meet all of the test standards consisted of providing a square frame formed of plastic rails laced with rubber bands. The frame was placed into the test chamber and the packaged parts were leaned against the rubber bands, approximating a 45.degree. angle. This approach proved inadequate because the framework would not lie flat in the chamber and thus, in combination with the approximate positioning, the required 45.degree. angle position could not be obtained consistently or, if obtained, maintained with certainty. In addition, the rubber bands would rapidly deteriorate in the salt fog during the test and eventually break which caused the test parts to fall to the bottom of the chamber. This approach was further inadequate because some portions of the metalized surface were either touched and/or were not properly exposed to the freely settling fog.
The present invention is directed to means and methods for unequivocally holding test parts of diverse shapes and sizes at the specified 45.degree. angle for the duration of the test in such a manner that the metalized surfaces and all test part surfaces are uniformly exposed to freely settling fog.